Sore shoulder: for those who think they are sports professionals

When your knee pops, slides, skips and rotates, you just may have ruptured your ACL. This is a common sporting injury that occurs in weekend sports enthusiasts and professional athletes alike. It is painful and takes a lot of rehabilitation, but ACL surgery is becoming routine.

The tennis ball sails over the net. You run towards it, slap it back across the net, but you can feel your knee give way. You crumble on the court, your tennis racket clattering beside you. You grab your knee, but already you can feel it starting to swell. It feels like it's come unhinged. Congratulations! You've just torn your ACL. You, along with every other pro athlete out there, have just experienced one of the most common orthopedic injuries. It is estimated that 200,000 injuries occur annually with 100,000 surgeries performed. Pick up the sports page and you can find the names of many high school, collegiate and professional athletes who all ended their seasons in need of ACL surgery. The knee is a complex joint, and there are many options that exist for the surgery to repair it. Work with your surgeon to determine the best medical course for you.

Anatomy of a knee: what the heck is an ACL, anyway?

The knee has more ligaments than a suspension bridge has cables. When a ligament is torn, the knee loses its stability and you have pain when walking. The acronym ACL stands for anterior cruciate ligament. The knee is essentially the meeting of the two bones of the leg: the femur, or thighbone, and the tibia, or shinbone. Your ACL prevents the shinbone from sliding out from underneath your thighbone and also keeps your knee from rotating abnormally. That's why when it’s torn your knee loses its stability. Unfortunately, due to the traumatic nature of ACL injuries, damage to other ligaments, meniscus, or padding, and protective cartilage are also quite common.

Types of grafts: where does one get a spare ACL?

When you completely tear your ACL, a new one needs to be inserted in its place. Your surgeon can get the new ACL from a few different sources. Each source has its pros and cons. One possible source is to take a sample from your patellar, or kneecap, tendon. The advantage of this is that it's your own tissue, but it can cause pain behind the kneecap postoperatively and can cause pain when kneeling. However, this is the gold standard with the rate of failure at only 1.9%. Another possibility is to take the tendon from the hamstring. Again, this is your own tissue, it offers a fast rate of healing, it has less risk of knee pain, but the rate of failure is 4.9%. A third option is called an allograft which is a ligament taken from a cadaver, or a deceased person. Although these grafts offer a high rate of success and are increasingly used in surgery, they do pose a risk for infection despite rigorous screening tests. Some studies have pointed to failure rates as high as 23% for these grafts, and researchers are unsure why this is so.

Complications of ACL surgery

As with any procedure, there are complications ACL surgery. Infection is the number one complication of ACL surgery, especially if you choose to have an allograft. The rate of infection for ACL surgery is 0.2 to 0.48%, but is higher with allograft donor tissue. Blood clots are the second most common side effect of ACL surgery, at a rate of only 0.12%. Outside of surgery, problems with the knee itself are likely. Instability in the knee can range anywhere from between 2.5 to 34% of all ACL surgery, and knee stiffness is reported in 5 to 25% of all surgical patients. Failure of the tendons that have been harvested, such as the patellar tendon or the hamstring tendon, can also occur due to weakening after the graft has been taken out. Kneecap pain is also common with patellar tendon harvesting, and it occurs in 4 to 56% of those who have this graft procedure.

References:

• American Academy of Orthopedic Surgeons; ACL Injury: Does It Require Surgery?; September 2009

Related articles:

• On bended knee: knee replacement is the surgery of the millennium
• Pop goes the knee

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